1. Field of the Invention
This invention relates to a process for observing structures of the eye for diagnostic purposes. More particularly, it relates to such a process for observing the tear film and of devitalized epithelial cells of the cornea and conjunctiva in order to aid in the diagnosis and to follow the progress of diseases of the surface of the eye and of the lacrimal system.
2. Description of the Prior Art
An aid to diagnosis of external diseases or superficial injuries of the eye is the introduction of small volumes of dye into the conjunctival cul-de-sac and examination of the eye with a biomicroscope. One dye commonly used for this purpose is fluorescein, whose green fluorescent color is observed by illumination with blue light. This allows the behavior of the tear film to be noted over the cornea, and it also reveals the presence of injuries to the superficial layer of epithelial cells of the cornea, which will be stained a bright green color by the dye. The use of fluorescein is of only limited value in making observations on the conjunctival membrane, because this membrane and its underlying sclera have a natural fluorescence when excited by blue light which conceals that of the dye itself. The fluorescein also penetrates the conjunctiva to some extent and makes the tear film and cells less visible in later stages.
Another dye commonly used is Rose Bengal, which colors injured cells pink and is used for observing devitalized cells in the conjunctival region, where they show up over the white background. However, Rose Bengal is painful when instilled into the eye and cannot be used in sufficient concentration to observe the tear film.
Because of these limitations in the known eye examination processes using dye to highlight the eye structures to be observed, a need remains for further improvement in such eye examination processes.